Capacitive sensor to sense an electric field, system and method to obtain it

ABSTRACT

A capacitive sensor able to sense an electric field comprises a shielding tubular body which extends axially along its own axis, an electric field sensor positioned within said shielding tubular body,
         a source electrode,   a mass of dielectric insulating material, in which the shielding tubular body (CTSa, CTSb) is formed by a mantle (Ma, Mb) having a plurality of first through openings (Aa, Ab), in which each of said first through openings (Aa, Ab) has an area comprised between a minimum of 0.1 mm 2  and a maximum of 3 mm 2 .       

     A system and a method to obtain said capacitive sensor.

TECHNICAL FIELD

The Present invention relates to a capacitive sensor for detecting an electric field, as well as a system and a method to obtain it.

More in particular, the present invention relates to a capacitive sensor to detect an electric field, in which said capacitive sensor comprises a shielding tubular body, an electric field sensor and a source electrode and a resin of dielectric insulating material, as well as a system and a method for obtaining said capacitive sensor.

BACKGROUND OF THE INVENTION

Currently, the capacitive sensors for detecting electrical fields, as well as systems and methods for obtaining them have a number of drawbacks.

A First drawback is due to the fact that the resin of dielectric material positioned into and around the shielding body includes vacuoles (air bubbles), with consequent phenomena of unwanted partial discharges.

A second drawback is due to the fact that the same resin is detached with respect to the shielding body and/or with respect to the electric field sensor and/or with respect to other bodies that make up the capacitive sensor, with consequent phenomena of unwanted partial discharges.

A Third drawback is due to the fact that the aforementioned resin is not perfectly adherent and/or it is not perfectly clinging and/or it is constrained with respect to the elements that make up the capacitive sensor and, therefore, as a result of aging, disjunctions occur between said resin and the above elements, in which said disjunctions cause unwanted partial discharges.

This drawback is particularly present when the capacitive sensor is used in an environment where the operating temperature (hot/cold) varies cyclically.

OBJECT OF THE INVENTION

The Purpose of the present invention is to obviate the above drawbacks.

The Invention, which is characterized by the claims, solves the problem to creates a capacitive sensor to sense an electric field, in which said capacitive sensor comprises:

a shielding tubular body, in which said shielding tubular body extends axially along its own axis and it configures a first open end;

an electric field sensor, in which said electric field sensor is positioned within said shielding tubular body;

a source electrode;

a mass of dielectric insulating material positioned within said shielding tubular body ad around said shielding tubular body, in which said capacitive sensor is characterized in that the shielding tubular body is formed by a mantle having a plurality of first through openings, and in that each of said first through openings has an area comprised between a minimum of 0.1 mm² and a maximum of 3 mm².

The Invention, which is characterized by the claims, also solves the problem of creating a system to obtain a capacitive sensor able to sense an electric field, in which said system is characterized in that it comprises:

a shielding tubular body, in which said shielding tubular body extends axially along its own axis and configures a first end and a second end;

an electric field sensor, in which said electric field sensor is positioned within said shielding tubular body;

a source electrode, positioned outside with respect to the shielding tubular body and near said first open end, or a source electrode having a shank coaxially positioned inside the shielding tubular body;

a mass of dielectric insulating material positioned within said shielding tubular body;

a mold comprising one or more pouring ducts;

in which the shielding tubular body is formed by a mantle having a plurality of first through openings;

in which said plurality of first through openings have an elongated shape;

in which each of the through openings has an elongated shape which configures a long size and a short size;

in which the long size of each through openings is oriented parallel with respect to the axis of the shielding tubular body;

in which the mass of dielectric insulating material disposed within the shielding tubular body is obtained by a compound that can take a first liquid/pasty state and a second solid state, in which by said pouring ducts the compound in its first liquid/pasty state is cast toward and against the outside of the mantle of the shielding tubular body.

The Invention, which is characterized by the claims, also solves the problem of creating a method to obtain a capacitive sensor to sense an electric field, in which said capacitive sensor comprises:

a shielding tubular body, in which said shielding tubular body extends axially along its own axis and configures a first end and a second end;

an electric field sensor, wherein said electric field sensor is positioned within said shielding tubular body;

a source electrode, arranged outside with respect to the shielding tubular body and near said first open end, or a source electrode having a shank coaxially positioned inside the shielding tubular body;

a mass of dielectric insulating material positioned within said shielding tubular body;

in which the shielding tubular body is formed by a mantle having a plurality of first through openings;

in which said plurality of first through openings have an elongated shape;

in which each through opening having an elongated shape configures a long size and a short size;

in which the long size of each through opening is oriented parallel with respect to the axis of the shielding tubular body;

in which the mass of dielectric insulating material disposed within the shielding tubular body is obtained by means of a compound that can take a first liquid/pasty state and a second solid state, and in which said method is characterized in that it comprises an operative step in which said compound in its first liquid/pasty state flows/passes through said plurality of first through openings inside the shielding tubular body in order to obtain the formation of the mass of insulating material within the same shielding tubular body.

By the capacitive sensor of the present invention, as well as by the related system and method to obtain it, a capacitive sensor having excellent characteristics with reference to the shield with respect to the surrounding electrical fields and it is obtained, in addition, a capacitive sensor without vacuoles and without any disjunctions it id obtained.

BRIEF DESCRIPTION OF THE DRAWINGS

Further characteristics and advantages of the present invention will be particularly evident from the following description of some preferred embodiments, here provided by way of non-limiting example and makes reference to the appended drawings, in which:

FIG. 1 illustrates a first embodiment of a capacitive sensor of the present invention;

FIG. 1A illustrates a second embodiment of a capacitive sensor of the present invention;

FIG. 1B illustrates a third embodiment of a capacitive sensor of the present invention;

FIG. 2 illustrates a shielding tubular body made by a sheet;

FIGS. 3 and 3A illustrate a shielding tubular body made by a sheet with first openings shaped like a rhombus, in which FIG. 3A is a sectional view with respect to the line 3A 3A of FIG. 3;

FIGS. 4 and 4A illustrate a shielding tubular body made by a sheet with first openings shaped in the form of ellipse, in which FIG. 4A is a sectional view with respect to the line 4A 4A of FIG. 4;

FIGS. 5 and 5A illustrate a shielding tubular body made by a sheet with first openings shaped in the form of rectangular slot, in which the FIG. 5A is a sectional view with respect to the line 5A 5A of FIG. 5;

FIGS. 6 and 6A illustrate a shielding tubular body made of sheet with first openings shaped like a hexagon, in which the FIG. 6A is a sectional view with respect to the line 6A 6A of FIG. 6;

FIG. 7 illustrates a shielding tubular body make up by mesh or grid or cloth of wires;

FIGS. 8 and 8A illustrate a shielding tubular body made by cloth of net having first openings shaped like a rhombus, in which FIG. 8A is a sectional view with respect to the line 8A 8A of FIG. 8;

FIGS. 9 and 9A illustrate a shielding tubular body made cloth of net having first openings shaped like a rectangle, in which the FIG. 9A is a sectional view with respect to the line 9A 9A of FIG. 9;

FIG. 10 shows an example of a mesh having crimped wires that are intertwined with each other;

FIG. 11 illustrates an example of a wire mesh having wires electro welded together;

FIG. 12 illustrates a system and a method for manufacturing the capacitive sensor illustrated in FIG. 1A.

BEST MODE OF CARRYING OUT THE INVENTION Capacitive Sensor FIG. 1, FIG. 1A and FIG. 1B

With reference to FIG. 1 it shows a first embodiment of a capacitive sensor indicated by the reference SC, in which said capacitive sensor comprises:

a shielding tubular body CTSa, which extends axially along its own axis X and which configures a first open end T1 a; an electric field sensor Sa, which is positioned within said shielding tubular body CTSa;

a source electrode E positioned in the proximity of said first open end T1 a; a mass of dielectric insulating material MDa, positioned into and around said shielding tubular body, CTSa, in which said mass is able to form a supporting structure.

The shielding tubular body CTSa is formed by a mantle Ma comprising a plurality of first through openings Aa, in which each first through opening Aa has an area between a minimum of 0.1 mm² and a maximum of 3 mm².

Each first through opening Aa has an elongated shape that configures a greater size D1 a and a smaller size D2 a, in which the greatest size D1 a is oriented parallel with respect to the axis X of the shielding tubular body CTSa.

The mantle Ma of said shielding tubular body CTSa has a thickness comprised between a minimum of 0.05 mm and a maximum of 1 mm.

With reference to the electric field sensor Sa it is positioned within said shielding tubular body CTSa and it is positioned in such way to form a capacitive coupling with the source electrode E.

Furthermore, preferably, the electric field sensor Sa comprises a plurality of second through openings SaA.

With reference to the source electrode E, in the specific embodiment of FIG. 1, it is positioned externally and spaced with respect to the shielding tubular body CTSa, positioned near the first open end T1 a and, more particularly, it is positioned axially spaced with respect to the first open end T1 a of said shielding tubular body CTSa.

With reference to FIGS. 1A and 1B, they illustrate, schematically, respectively, a second and a third embodiment of a capacitive sensor, both object of the present invention, in which said two embodiments are indicated with the references SCa and SCb respectively.

With reference to the following description, the references that have the letter “a” refer to FIG. 1A and the references that have the letter “b” refer to FIG. 1B.

With reference to said FIGS. 1A and 1B, the capacitive sensor, SCa/SCb, comprises:

a shielding tubular body, CTSa/CTSb, which extends axially configuring a longitudinal axis, Xa/Xb, a first head, T1 a/T1 b, and a second head, T2 a/T2 b; an electric field sensor, Sa/Sb, positioned within said shielding tubular body, CTSa/CTSb;

a voltage source electrode, Ea/Eb, which comprises a stem, Ea1/Eb1, which extends axially, Xa/Xb, within said shielding tubular body, CTSa/CTSb; a mass of dielectric material, MDa/MDb, disposed within said shielding tubular body, CTSa/CTSb, as well as around said elements.

The shielding tubular body CTSa/CTSb is formed by a mantle, Ma/Mb, having a plurality of first through-openings, Aa/Ab, in which each first through-opening, Aa/Ab, has an elongated shape that configures a greater size, D1 a/D1 b, and a minor size, D2 a/D2 b, in which the greater size, D1 a/D1 b, of each first through-opening, Aa/Ab, is oriented parallel to the axis, Xa/Xb, of the shielding tubular body, CTSa/CTSb.

Preferably, each first through opening Aa/Ab has an area between a minimum of 0.1 mm² and a maximum of 3 mm², and the mantle Ma/Mb of said shielding tubular body CTSa/CTSb has a thickness comprised between a minimum of 0.05 mm and a maximum of 1 mm.

With reference to the electric field sensor, Sa/Sb, it is disposed within said shielding tubular body, CTSa/CTSb, and said electric field sensor, Sa/Sb, is positioned in such a way as to form a capacitive coupling with said source electrode, Ea/Eb.

The electric field sensor, Sa, Sb, preferably, has a plurality of second through openings, SaA, SbA.

With particular reference to the second embodiment illustrated in FIG. 1A, the capacitive sensor SCa comprises a shielding tubular body CTSa, an electric field sensor Sa, a source electrode voltage Ea, a base Za, and a mass of dielectric material Ma formed, for example, by a resin dielectric material, positioned inside the shielding tubular body and outside the same shielding tubular body.

With reference to the shielding tubular body CTSa, it extends axially and configures a longitudinal axis Xa, a first open end T1 a and a second closed head T2 a.

With reference to the electric field sensor Sa, it is positioned within said shielding tubular body CTSa by the base Za, and it is positioned in such a way as to form a capacitive coupling with the source electrode Ea.

Furthermore, preferably, said electric field sensor Sa has a shape like a cup and/or a spherical cap with opening facing the electrode Ea and it is preferably formed by a mantle having a plurality of second through openings SaA.

With reference to the source electrode Ea, it is positioned near to the first end T1 a of the shielding tubular body CTSa and, preferably, said source electrode Ea has a shape like a funnel (trumpet) with rounded sides and, substantially, it configures a stem Ea1 having an axis which is coaxial within respect to the axis of said shielding tubular body CTSa, an optional head Ea2 positioned near said first head open T1 a and outside with respect to the same shielding tubular body CTSa, and a free rounded end Ea3 which extends toward the second end T2 a, in which this end E3 a is axially spaced with respect to the electric field sensor Sa.

With reference to the base Za, it is positioned near the second end T2 a of the shielding tubular body CTSa and, preferably, it has a shape like a cylindrical pyramid, and it configures a plurality of coaxial cylinders having different diameters between them.

Said base Za comprises a first cylinder Z1 a which supports in position the electric field sensor Sa, a second cylinder Z2 a which is mechanically coupled with the second end T2 a of the shielding tubular body CTSa, and a third cylinder, Z1 a, which is positioned outside with respect to the shielding tubular body CTSa.

Said shielding tubular body CTSa is formed by a mantle Ma comprising a plurality of first through openings Aa, in which each first through opening Aa has an elongated shape configuring a greater size D1 a and a smaller size D2 b, in which the greater size D1 a is oriented parallel with respect to the axis Xa of the shielding tubular body CTSa.

Preferably, each first through opening Aa has an area between a minimum of 0.1 mm² and a maximum of 3 mm², and the mantle Ma of said shielding tubular body CTSa has a thickness comprised between a minimum of 0.05 mm and a maximum of 1 mm.

With reference to the shielding tubular body CTSa having the first openings Aa, as better described below, said shielding tubular body CTSa can be obtained by a expanded metal sheet, or by perforated metal sheet, or by a mesh/grid/cloth formed by a plurality of wires.

With particular reference to the third embodiment illustrated in FIG. 1B, the capacitive sensor SCb comprises a shielding tubular body CTSb, an electric field sensor Sb, a live source electrode Eb having a stem E1 b which extends within said shielding tubular body CTSb, and a mass of dielectric material Mb formed, for example, by a resin of dielectric material positioned inside the tubular body and outside of the same shielding tubular body CTSb.

Said electric field sensor Sb is positioned radially spaced with respect to said stem Eb1 in order to form a capacitive coupling between them and, preferably, said electric field sensor Sb has a shape in the form of foil having a plurality of second through openings SbA.

With reference to the electrode source Eb, it includes said shank Eb1, a first optional head Eb2, and a second optional head Eb3.

Said first head Eb2 is positioned externally with respect to the shielding tubular body CTSb and, more particularly, it is positioned near and spaced with respect to the axial end of the first head T1 b.

Said stem Eb1 has an axis Xb which extends axially within said shielding tubular body CTSb.

Said second head Eb3 is positioned externally with respect to the shielding tubular body CTSb and, more particularly, it is positioned near and spaced with respect to the ends of the second head T2 b.

How already provided in the first embodiment of FIG. 1A, said shielding tubular body CTSb is formed by a mantle Mb comprising a plurality of first through openings Ab, in which each single through opening Ab has an elongated shape that configures a greater size D1 b and a smaller size D2 b, in which the greatest size D1 b is oriented parallel with respect to the axis Xb of the shielding tubular body CTSb.

Still as provided in the first embodiment of FIG. 1A, preferably, each through opening Ab has an area between a minimum of 0.1 mm² and a maximum of 3 mm², and the mantle Mb of said shielding tubular body CTSb has a thickness comprised between a minimum of 0.05 mm and a maximum of 1 mm.

As provided in the first embodiment of FIG. 1A, preferably, the shielding tubular body CTSb with openings Ab, as more detailed below, can be obtained by an expanded metal sheet, or by a perforated metal sheet, or by a mesh/grid/cloth composed by a plurality of wires.

Sheet with First Openings (Expanded or Perforated)

With reference to FIG. 2, it illustrates a shielding tubular body, CTSa, CTSb, of the type described above with reference to FIGS. 1, 1A et 1B, obtained by a sheet of expanded metal network (micro-expanded) or by means of a perforated metal sheet, in both cases, comprising the first openings Aa/Ab.

More particularly said shielding tubular body, CTSa, CTSb, can be realized by a metal sheet having first openings Aa/Ab, folded in the manner of a tubular, and comprising a first weld bead C20 which extends axially, in which said weld bead C20 is able to join together two axial edges C21 and C22 of the folded sheet in the form of tubular.

Preferably, said shielding tubular body, CTSa, CTSb, also comprises at least a second bead C30 of weld material, disposed around at least a head T2 of said shielding tubular body, CTSa, CTSb.

With reference to FIG. 3 e 3A, they illustrate a first preferred embodiment of a shielding tubular body 10 obtained by means of an expanded metal sheet or perforated metal sheet of the above type.

Said shielding tubular body 10 is formed by a mantle 11 having a plurality of first through openings 12 shaped like a rhombus, in which each rhombus configure a long diagonal 13 and a short diagonal 14, in which the long diagonals 13 of each rhombus are oriented parallel with respect to the axis, Xa/Xb, of the shielding tubular body 10.

With reference to FIGS. 4 and 4A, they illustrate a second preferred embodiment of the shielding tubular body 110 obtained by means of an expanded metal sheet or perforated metal sheet of the above type.

Said shielding tubular body 110 is obtained by a mantle 111 having a plurality of first through openings 112 which are shaped in the form of an ellipse, wherein each ellipse configures a long axis 113 and a short axis 114, in which the long axis 113 of each ellipse is oriented parallel with respect to the axis, Xa/Xb, of the shielding tubular body 110.

With reference to FIGS. 5 e 5A, they illustrate a third preferred embodiment of the shielding tubular body 210 obtained by means of an expanded metal sheet or a perforated metal sheet of the above type.

Said shielding tubular body 210 is formed by a mantle 211 comprising a plurality of first through openings 212 that are shaped in the manner of an oblong slot, wherein each oblong slot configures a long axis 213 and a short axis 214, in which the long axis 213 of each oblong slot are oriented parallel with respect to the axis, Xa/Xb, of the shielding tubular body 210.

With reference to FIGS. 6 e 6A, they illustrate a fourth preferred embodiment of the shielding tubular body 310 obtained by means of a network of an expanded metal sheet or perforated metal sheet of the above type.

Said shielding tubular body 310 is formed by a mantle 311 comprising a plurality of first through openings 312 that are shaped in the form of an elongated hexagon, wherein each elongated hexagon has a long axis 313 and a short axis 314, in which the long axes 313 of each elongated hexagon are oriented parallel with respect to the axis, Xa/Xb, of the shielding tubular body 310.

Mesh or Cloths with First Openings

With reference to FIGS. 1 and 1A, said shielding tubular body, CTSa/CTSb, can be obtained by a mesh or grid or cloth, in which said mesh or grid or cloth comprises wires of conductor material, in which said wires are intersect and/or intertwined with each other, in which said mesh or grid or cloth configures said plurality of first openings, Aa/Ab.

Preferably, each first opening, Aa/Ab, has an area between a minimum of 0.3 mm² and a maximum of 1.5 mm².

With reference to FIG. 7, it illustrates shielding tubular body, CTSa, CTSb, of the type above described with reference to FIGS. 1, 1A and 1B, here formed by a sheet of mesh or grid or cloth obtained by metal wires.

Said shielding tubular body, CTSa/CTSb, comprises a first weld bead C120 which extends axially along the mantle, Ma/Mb, in which said first weld bead C120 is able to join together the two axial opposite edges, C121, C122, of a sheet of mesh or grid or cloth wrapped in the form of a tubular.

Preferably, said shielding tubular body, CTSa/CTSb, comprises one or more second axial beads, C123, C124, of weld material, positioned on the mantle, Ma, Mb, in which said second beads C123, C124 act as reinforcement for the structure of the shielding tubular body.

Preferably, said shielding tubular body, CTSa/CTSb, comprises at least one third bead, C130, of weld material, positioned around at least a head T2 of the shielding tubular body, CTSa/CTSb.

Said first bead C120 and/or said one or more second beads C123 C124 and/or said third bead C130, are preferably obtained by means of a tin alloy.

With reference to FIGS. 8 and 8A, they illustrate a first preferred embodiment of a shielding tubular body R10 obtained by a mesh or grid or cloth comprising metal wires.

Said shielding tubular body R10 is formed by a mantle R11 having a plurality of first openings R12 shaped like a rhombus, where each rhombus configures a long diagonal R13 and a short diagonal R14, in which the long diagonals R13 of each rhombus are oriented parallel with respect to the longitudinal axis, Xa/Xb, of the shielding tubular body.

With reference to FIGS. 9 and 9A, they illustrate a second preferred embodiment of a shielding tubular body R210 obtained by a mesh or grid or cloth comprising metal wires.

Said shielding tubular body R210 is formed by a mantle R211 having a plurality of first openings R212 shaped like a rectangle, in which each rectangle configures a longer side R213 and a shorter side R214, in which the longer sides of each rectangle are oriented parallel with respect to the longitudinal axis, Xa/Xb, of the shielding tubular body.

With reference to the embodiments of the shielding tubular body obtained by a mesh or grid or cloth comprising metal wires, said wires can have a circular cross section and, preferably, said circular cross section has a diameter comprised between a minimum of 0.01 mm and a maximum of 1 mm.

Said wires of the mesh or grid or cloth, may also have an elliptical cross section, in which said elliptical cross section preferably has an area comprised between a minimum of 0.01 mm² and a maximum of 0.8 mm², or, a square cross section, in which said square cross section has an area comprised between a minimum of 0,001 mm² and a maximum of 0.8 mm², or a hexagonal cross section, in which said hexagonal cross section has an area comprised between a minimum of 0.01 mm² and a maximum of 0.8 mm².

With reference to FIG. 10, the mesh or grid or cloth above mentioned used to obtain the shielding tubular body may be formed by crimped wires that are intertwined with each other.

Still with reference to FIG. 10, by way of not limiting example, said mesh or grid or cloth can comprise a first set of wires and a second set of wires, in which the first set of wires intersect the second set of wires forming a grid which configures the above first openings, wherein said first set of wires and said second set of wires form points of intersection/contact, in which said points of intersection/contact configure segments of wires, in which in said point of intersection/contact the respective first wires and the respective second wires are free to move with respect to each other (as flexure) with limited freedom of movement, as for example up to a maximum displacement of about 0.5 mm.

With reference to this embodiment, during the hot casting of the resin in the liquid state and during the cooling of the same resin, with relative thermo-expansion and thermo-shrinking, the wires of the mesh or grid or cloth adhere to the same resin.

With reference to FIG. 11, the sheet of the mesh or grid or cloth above mentioned used to obtain the shielding tubular body may comprise electro welded wires, in which said wires intersect each other.

Electric Field Sensor

With reference to FIGS. 1 and 1A, the capacitive sensor Sa preferably has a shape in the form of a cup and/or spherical cap with the opening facing the electrode Ea, in which said cup and/or spherical cap is formed by a mantle having a plurality of second through openings SaA, in which said second through openings SaA preferably have the same dimensions of the openings Aa and Ab of the shielding tubular body CTSa, CTSb.

With reference to FIG. 1B, the capacitive sensor Sb preferably has a shape in the form a foil and includes a plurality of second through openings SbA, in which even said second through openings SbA preferably have the same sizes of the openings Aa and Ab of the shielding tubular body CTSa, CTSb.

System to Obtain a Capacitive Sensor

With reference to FIG. 12, it shows a preferred embodiment of a system used to obtain a capacitive sensor to detect an electric field, i.e. a capacitive sensor of the type described above with reference to FIG. 1 or 1A.

In this context, the same system can also be used to obtain in the same way a capacitive sensor for detecting an electric field of the type described above with reference to FIG. 1B.

In this context, in the following description, the references with the letter “a” refer to the capacitive sensor of FIGS. 1 and 1A, while references with the letter “b” refer to the second capacitive sensor of FIG. 1B.

With reference to the above FIG. 12, and substantially synthetically, the system comprises:

a tubular body shielding, CTSa/CTSb, in which said tubular body shielding extends axially along its own axis Xa/Xb and configures a first head T1 a/T1 b and a second head T2 a/T2 b;

an electric field sensor Sa/Sb, in which said electric field sensor is positioned within said shielding tubular body CTSa/CTSb;

a source electrode E arranged externally with respect to said shielding tubular body and positioned near the first open end, or a source electrode, Ea/Eb, having a stem, Ea1/Eb1, positioned coaxially into the shielding tubular body, CTSa/CTSb;

a mass of dielectric insulating material, Ma/Mb, positioned into said shielding tubular body CTSa/CTSb, and around these elements;

a mold 100 comprising one or more pouring ducts 101 a, 101 b, etc.

With reference to the tubular body shielding, CTSa/CTSb, it is formed by a mantle, Ma/Mb, comprising a plurality of first through-openings, Aa/Ab, in which said first through openings Aa/Ab have an elongated shape intended to configure a long size, D1 a/D1 b, and a small size, D2 a/D2 b, in which the long size, D1 a/D2 b, of each through-opening, Aa/Ab, is oriented parallel to the axis, Xa/Xb, of the shielding tubular body, CTSa/CTSb.

With reference to the mass of dielectric insulating material, Ma/Mb, positioned inside the shielding tubular body, CTSa/CTSb, said mass Ma/Mb is obtained by means of a compound that can take a first liquid/pasty state and a second solid state.

By means of said system, through the conduits casting 101 a, 101 b, etc., the particular compound in its first liquid/paste state is poured toward and against the outside mantle Ma/Mb of the shielding tubular body CTSa/CTSb, and said compound in its first state liquid/pasty through said plurality of first through openings Aa/Ab flows into the shielding tubular body CTSa/CTSb.

Still with reference to said system, preferably, said shielding tubular body is positioned and supported in a cantilevered manner within the mold 100, by means of its head T2 a associated with a base Za, where the latter is supported in position by the mold 100.

Still with reference to this system, more preferably, said source electrode Ea is positioned in a cantilever manner within the mold 100 by a head E2 a supported in position by the mold 100.

Method to Get a Capacitive Sensor by the System

With reference to FIG. 12 and to the above description regarding the system to get a capacitive sensor, the present invention also concerns a method for obtaining said capacitive sensor, wherein said method is characterized in that it comprises an operative step in which said compound in its first liquid/pasty state flows/passes through said plurality of first through openings Aa/Ab, inside the tubular body shielding, CTSa/CTSb, in order to obtain the formation of the mass of insulating material, MDa/MDB within the same shielding tubular body CTSa/CTSb.

By this methodological technical feature, the liquid/pasty compound is positioned within the shielding tubular body CTSa/CTSb without formation of air bubbles and with perfect adhesion between the shielding tubular body CTSa/CTSb and resin MDa/MDb.

Compound for the Formation of the Mass of Insulation Dielectric Material

With reference to the mass of dielectric material, MDa/MDb, preferably, it comprises an epoxy resin of the insulating dielectric material, or a compound of polyester.

The above description of the capacitive sensor, of the system and of the method to obtain it is provided solely by way of non-limiting example, and therefore, said sensor, said system and said method can be modified or varied in any way suggested by experience and/or its use or application within the scope of the following claims.

The following claims consequently also form an integral part of the above description. 

1. A capacitive sensor to sense an electric field, the capacitive sensor comprising: a shield tube that extends axially along its own axis and has a first open end; an electric field sensor that is positioned within said shield tube; a source electrode; a mass of dielectric insulating material positioned within said shield tube and around said shield tube, the shield tube being formed by a jacket having a plurality of first through openings, each of said first through openings having an area comprised between a minimum of 0.1 mm² and a maximum of 3 mm².
 2. The capacitive sensor according to claim 1, wherein said plurality of first through openings each have an elongated shape, each through opening having an elongated shape has a long dimension and a short dimension, and the long dimension of each through opening is oriented parallel with respect to the axis of the shield tube.
 3. The capacitive sensor according to claim 1, wherein said electric field sensor has a plurality of second through openings.
 4. The capacitive sensor according to claim 1, wherein said source electrode is positioned externally with respect to the shield tube and said source electrode is positioned axially spaced from the first open end of said shield tube.
 5. The capacitive sensor according to claim 1, wherein the shield tube comprises a first open end and a second opposite closed end; the source electrode comprises a shank and a free end; the shank extends axially within said shield tube and toward the second end of the shield tube; the free end is positioned within said shield tube, and the free end is axially spaced from the electric field sensor.
 6. The capacitive sensor according to claim 1, wherein the shield tube comprises a first open end and an opposite second closed end; the source electrode comprises a head a shank and a free end; the head is positioned near the first open end of the shield tube and outside with respect to the same shield tube; the shank extends axially within said tubular shielding body and toward the second end of the shield tube; the free end is positioned within said shield tube, and the free end is axially spaced from the electric field sensor.
 7. The capacitive sensor according to claim 5, wherein the electric field sensor has a shape like a cup and/or a spherical dome with opening facing the source electrode.
 8. The capacitive sensor according to claim 1, wherein the shield tube comprises a first open end and a second opposite open end; the source electrode comprises a shank; the shank extends axially within and along said shield tube and the electric field sensor is positioned radially spaced from said shank.
 9. The capacitive sensor according to claim 1, wherein the shield tube comprises a first open end and a second opposite open end; the source electrode comprises a first head a shank and a second head; the first head is positioned near said first open end and externally with respect to the shield tube; the second head is positioned near said second open end and externally with respect to the shield tube shielding; the shank extends axially within and along said shield tube and the electric field sensor is positioned radially spaced from said shank.
 10. The capacitive sensor according to claim 1, wherein said shield tube is formed by a metal sheet having first through openings and folded into a tube, and the shield tube comprises a first weld bead that extends axially and act to join together two axial edges of the folded sheet into a tube.
 11. The capacitive sensor according to claim 1, wherein said shield tube is formed by a mesh or grid or cloth, the mesh or grid or cloth comprises wires that intersect each other; the mesh or grid or cloth has said plurality of first through openings; and the wires are made of conductive material.
 12. The capacitive sensor according to claim 11, wherein said mesh or grid or cloth comprises a first set of wires and a second set of wires; the first series of wires and said second set of wires intersect each other; the first series of wires and said second set of wires define a mesh/grid/cloth having through openings; the first series of wires and said second set of wires define points of intersection/contact between them; the first series of wires and said second set of wires define segments of wire delimited by said points of intersection/contact, and in these points of intersection/contact the respective first wires and the respective second wires are movable relative to each other.
 13. A system for making a capacitive sensor to sense an electric field, wherein said system comprises: a shield tube, in which said shield tube extends axially along its own axis and has a first end and a second end; an electric field sensor, in which said electric field sensor is positioned within said shield tube; a source electrode, positioned outside with respect to the shield tube and near said first open end, or a source electrode having a shank positioned coaxially inside the shield tube; a mass of dielectric insulating material positioned within said shield tube; a mold comprising one or more pouring ducts; the shield tube is formed by a jacket having a plurality of first through openings; the plurality first through openings have an elongated shape; each through opening having an elongated shape has a long dimension and a short dimension; the long dimension of each through opening is oriented parallel with respect to the axis of the shield tube; that the mass of dielectric insulating material disposed within the shield tube is obtained by a compound that can take a first liquid/pasty state and a second solid state, and by said pouring ducts the compound in its first liquid/pasty state is cast toward and against the outside of the jacket of the shield tube.
 14. A method of making a capacitive sensor to sense an electric field, in which said capacitive sensor comprises: a shield tube that extends axially along its own axis and has a first end and a second end; an electric field sensor that is positioned within said shield tube; a source electrode, arranged outside with respect to the shield tube and near said first open end, or a source electrode having a shank positioned coaxially inside the shield tube; a mass of dielectric insulating material positioned within said shield tube; that the shield tube is formed by a jacket having a plurality of first through openings; that said plurality of first through openings have an elongated shape; that each through opening having elongated shape has a long dimension and a short dimension; that the long dimension of each through opening is oriented parallel with respect to the axis of the shield tube; the mass of dielectric insulating material disposed within the shield tube is obtained by a compound that can take a first liquid/pasty state and a second solid state, and said method is wherein it comprises an operative step in which said compound in its first liquid/pasty state flows/passes through said plurality of first through openings inside the tubular body shielding in order to form the mass of insulating material within the same shield tube. 